Electroluminescent lamp with built-in rearwardly-disposed input terminals



May 17, 1966 l. E. BUCK. JR

ELEGTROLUMINESCENT LAMP WITH BUILT-IN REARWARDLY-DISPOSED INPUTTERMINALS Filed Feb. 25, 1963 FlG.3.

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INVENTOR. IVAN E. BUCK,JR.

W- .}LL)7iL- 3,252,035 ELECTROLUMINESCENT LAMP WITH BUILT-INREARWARDLY-DISPOSED INPUT TERMINALS Ivan E. Buck, In, East Orange, N.J.,as'signor to Westinghouse Electric Corporation, Pittsburgh, Pa., :1corporation of Pennsylvania Filed Feb. 25, 1963, Ser. No. 260,793 6Claims. (Cl. 313-108) This invention relates to electroluminescentdevices and has particular reference to an electroluminescent lamphaving an improved terminal structure.

One of the most troublesome problems encountered in the manufacture ofelectroluminescent lamps is that of making a durable electricalconnection with the electrodes, especially the light-transmittingelectrode on the face of the lamp. This is particularly true in the caseof so-called metal-ceramic type lamps in which the phosphor particlesare embedded in glass that has been fired onto a metal base member,which serves as one of the electrodes, and a transparent conductivecoating is applied to the glass-phosphor layer to form the secondelectrode.

' It is desirable in most installations that both the electrodeconnections be made at the rear or opaque side of the lamp. In order toaccomplish this, it was heretofore necessary to connect one of the lampterminals to the light-transmitting electrode by means of an insulatedlead that extended around the edge of the lamp. This fjumper type leadconstruction leaves much to be desired insofar as it requires that anopening be provided in the protective cover coat on the face of the lampand thus exposes the electrical connection to attack by moisture orelectrolysis. In addition, the lead wire insulation may break down inuse resulting in a short circuit which would ruin the lamp. Moreover,since the connection is made with a portion of the lightemitting face ofthe lamp, this portion remains dark when the lamp is energized thus,detracting from the appearance of the lamp and its performance.

It is accordingly the general object of the present invention to providean improved terminal constructionfor an electroluminescent device thatwill avoid the aforementioned problems and disadvantages of the priorart.

Another object is the provision of an electroluminescent lamp havingterminals that are simple and inexpensive to United States Patent makeand which will not detract from either the performcoat and other strataof the cell structure through which 4 connection with both of theelectrodes can be made. The light-emitting face is thus not marred byany dark regions when the lamp is energized and the protective coatingremains intact over the entire face of the lamp.

In the case of a metal-ceramic type lamp, the rearwardly-extending edgeor terminal segment is produced by using a rigid base member of theproper shape and Patented May 17, 1966 then forming the various layerson this member in the usual manner. In the case of an all-plastic lamp,the lamp may be constructed in the form of a fiat panel in the regularmanner and then a preselected edge portion can be heat-softened and benttoward the back of the lamp to provide the rearwardly-extending terminalstrip. This technique can also be used if the base member is made froman easily deformable metal such as aluminum and the various laminationsconstituting the electroluminescent cell are flexible enough towithstand the stresses produced by the bending operation.

A better understanding of the invention will be obtained from theaccompanying drawing, wherein:

FIGURE 1 is a perspective View of a metal-ceramic typeelectroluminescent lamp embodying the present in vention; v

FIG. 2 is a similar view of the reverse side of the lamp showing thebent-over terminal strips and exposed contacts or portions thereof atthe back of the lamp;

FIG. 3 is an enlarged cross-sectional view through the lamp along thereference line III-III of FIG. 1, in the direction of the arrows, amedial portion of the lamp being omitted to facilitate the illustration;and

FIGS. 4 to 8 are fragmentary side elevational views of alternative lampembodiments illustrating other configurations that can be used informing the terminal portions.

While the improved terminal construction of the present The invention InFIG. 1, there is shown atop perspective view of a metal-ceramic lamp 10having a rectangular light-emitting face 12 and rearwardly-extendingstrips or edge portions A and B that comprise integral parts of the lampand are bent back away from the light-emitting face into overlappingrelationship with the back of the lamp. As shown in FIG. 2, openings 22and 24 are provided in the layers that comprise the cell structure andoverlie the exposed faces of the strips through which each of therespective electrodes can be engaged.

The construction of the lamp 10 and the improved terminal means areillustrated in greater detail in the cross-sectional view shown in FIG.3. As indicated, the lamp consists of the usual metal base electrode 14,such as an iron or aluminum plate for example, one side of which iscovered with a fired-on glass-dielectric-phosphor layer 16. Thiscomposite layer is, in turn, coated with a radiation-transmittingelectrode 18 such as a layer of tin oxide or the like. Protectionagainst water vapor and other atmospheric contaminants is obtained bycoating the light-transmitting electrode 18 with a cover coat 20 ofsuitable moisture-impervious material. In the metal-ceramic lamp hereshown, theelectrolumines cent phosphor particles are embedded in asuitable glass and the protective coating 20 consists of a glass layerhaving a suitably low firing temperature.

As will be noted in FIG. 3, contrary to the conventional practice ofusing a flat plate as the base electrode, the base electrode inaccordance with the present inven- 1 The aforementionedphosphor-dielectric layer 16, lighttransmitting electrode 18 andprotective coating 20 are applied in the usual fashion so that theycover not only the flat body portion of the base electrode 14 but extendaround the bent sides thereof and cover the exposed surfaces of theoverlapped rearwardly-protruding edge or terminal portions A and B. Theinput terminals, accordingly, comprise anintegral part of the lamprather than separate components as was the case heretofore.

As is illustrated in FIGS. 2 and 3, the phosphordielectric layer 16 andthe protective coating 20 are removed from a preselected portion of thebase electrode 14 to provide an opening 22 through which electricalconnection with the base electrode can be made. A similar opening 24 isprovided in the other edge portion B by removing the protective layer 20to expose the underlying light-transmitting electrode 18. Thus, the lamp19 can be energized without obstructing the lightemitting face 12 byconnecting suitable lead conductors 26, as shown in FIG. 3, to theexposed parts of the base electrode 14 and light-transmitting electrode18 located at the back of the lamp.

As is indicated in FIG. 3, additional protection from gaseouscontaminants can be obtained by filling the cavity at the back of thelamp It] with a moisture-impervious material, such as glass or epoxyresin, and thus providing a protective backing 28 (shown in dottedoutline} that extends across and seals off the back of the lamp,including the terminal openings 22 and 24, from the atmosphere.

As will be obvious, the openings 22 and 24 can be made by removing theoverlying layers or by masking those portions of the bent-over edgeportions A and B while the layers are being deposited.

Alternative embodiments Various other configurations can also be used toform the rearwardly-extending terminal or edge portions, as shown inFIGS. 4 to 8. In the lamp a shown in FIG. 4, the edge portion A is bentback sharply away from the light-emitting face 12d so that it seatsagainst the body portion of the lamp. In FIG. 5, there is shown a lamp10b in which the bend 30 is formed around a wire 32 that is tightlylocked in and extends along the bead to provide a beaded edge thereat.

In FIG. 6, there is shown another lamp embodiment 100 wherein a bend 34having a much larger radius of curvature is used so that only the endsegment of the lapped edge portion A is seated against the back of thelamp This construction provides an enlarged bead and an eyelet-likeopening 36 that extends along the lapped edge of the lamp.

In the lamp 10d shown in FIG. 7, a U-shaped bend 38 is employed so thatthe edge portion A overlies but is not seated against the fiat bodyportion of the lamp.

The lamp 10e shown in FIG. 8 is provided with an edge portion A that isjoined to the body portion of the lamp by a right angle bend 40 and thusis disposed approximately normal to and rearwardly of the lighted face12e of the lamp.

Electrical connection with the bent-over edge portions A in each of theabove-described alternative embodiments is eifected by means of suitablecontactors and conductors,

as indicated by the arrows in the respective figures.

It will be appreciated from the foregoing that the objects of theinvention have been achieved insofar as a very simple and inexpensiveterminal construction for electroluminescent devices has been providedwhich not only preserves the integrity of the protective coating butenables electrical connection with both of the electrodes to beconveniently effected at the back of the device without in any wayinterfering with or obscuring the light-emitting front face of thedevice.

While several embodiments have been illustratedand described, variouschanges in both the configuration and organization of parts can be madewithout departing from the spirit and scope of the invention.

I claim:

1. An electroluminescent lamp comprising, a metallic substantially flatbase electrode having a bent edge portion that extends rearwardly and isdisposed in overlapping relationship with the body portion of said baseelectrode,

a continuous phosphor-dielectric layer on the face of said baseelectrode opposite the bent-over edge portion thereof and extendingaround to and covering the outwardly disposed face of said edge portion,and

a second electrode comprising a continuous radiationtransmitting layerof electrically conductive material overlying said phosphor-dielectriclayer,

said base electrode being accessible at the back of said lamp through anopening in portions of said phosphor-dielectric layer and said secondelectrode that cover the bent-over edge portion of said base electrode,whereby segments of both of said electrodes located behind thelight-emitting face of said lamp are exposed for direct electricalconnection and thus provide integral rearwardly-disposed input terminalsfor the lamp.

2. An electroluminescent lamp as set forth in claim 1 wherein,

said radiation-transmitting electrode is coated with a protective layerof radiation-transmitting material, and

access openings to the exposed part of the bent-over edge portion ofsaid base electrode and a portion of said radiation-transmittingelectrode are provided in said protective coating.

3. An electroluminescent lamp as set forth in claim 1 wherein a wiremandrel is locked in and extends along the bend joining the bent-overedge portion to the body portion of said base electrode and thusprovides a protruding bead at said bend.

4. An electroluminescent lamp as set forth in claim 1 wherein the radiusof the bend connecting the bent-over edge portion with the body portionof said base electrode is such that an enlarged bead and opening aredefined by and extend along said bend.

5. An electroluminescent lamp as set forth in claim 1 wherein the saidbent-over edge portion is spaced from the underlying body portion ofsaid base electrode.

6. An electroluminescent device comprising;

a rigid base member having a rearwardly-extending portion that isdisposed in overlapping relationship with the body portion of said basemember,

the face of said base member opposite the rearwardlyextending portionbeing electrically conductive and comprising a first electrode thatextends around to and covers the outwardly-disposed surface of saidrearwardly-extending portion,

a continuous phosphor-dielectric layer overlying and covering said firstelectrode,

a second electrode comprising a continuous radiationtransmitting layerof electrically-conductive material that overlies and covers saidphosphor-dielectric layer, and

a protective coating of radiation-transmitting material overlying saidsecond electrode,

said first electrode being accessible through a first opening inportions of said phosphor-dielectric layer, second electrode andprotective coating that cover the realrwardly-extending portion of saidbase member,

said second electrode being accessible through a second opening inanother portion of said protective coating that overlies therearwardly-extending portion of said base member,

whereby segments of'both electrodes carried by said 5 6rearwardly-extending portion of the base member 2,900,545 8/ 1959 Rulonet a1 313-408 1 are exposed for direct electrical connection and thus2,922,912 1/ 1960 Miller 313-408 provide integral input terminalslocated at the back 3,043,979 7/ 1962 Van Geel et a1 313-108 of saiddevice. 3,153,166 10/ 1964 Thornton et a1 313-108 5 References Cited bythe Examiner GEORGE N. WESTBY, Primary Examiner.

UNITED STATES PATENTS ROBERT SEGAL, Examiner.

2,714,683 8/1955 Jenkins 313-109 JUDD, Assistant Examiner-

